Ancient Toothy Fish Once Prowled Arctic Waters

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A large predatory fish with a fearsome mouth once prowled ancient
North American waterways, suggests an analysis of fossilized
remains of the beast.

The lobe-finned fish, now called Laccognathus embryi,
probably grew to about 5 or 6 feet long (1.5 to 1.8 meters) and
had a wide head with small eyes and robust jaws lined with large
piercing teeth. The beast was likely a bottom-dweller, waiting on
the seafloor to lunge at prey passing by. [ Album
of Scary Sea Creatures ]

"I wouldn't want to be wading or swimming in waters where this
animal lurked," said study researcher Edward Daeschler, a curator
of vertebrate zoology at the Academy of Natural Sciences in
Philadelphia.

The
lobe-finned fish likely preyed on armored placoderms and
lungfish, lead author Jason Downs, also of the Academy of Natural
Sciences, told LiveScience. "Laccognathus embryi, with
its powerful jaws and long, sharp teeth is certainly a predatory
animal that is likely to have eaten the other aquatic vertebrates
that lived in the same streams and rivers."

The team discovered the 375-million-year-old fish fossil on
Ellesmere Island in the remote Nunavut Territory of Arctic
Canada, though back then conditions would have been subtropical,
the researchers said.

In the past, the researchers also discovered
Tiktaalik roseae, a transitional animal considered a
"missing link" between fish and the earliest limbed animals,
side-by-side with L. embryi at the same site. That
suggests the two lived side-by-side as well, the researchers
speculate.

"Both are predators, and there is certainly a possibility that
they competed for prey," Downs said. "It is also possible that
they lived at different depths or even employed different feeding
strategies that would have enabled them to establish unique
feeding niches in these environments."

Though the team discovered the first L. embryi fossil
some 10 years ago, they only recently described the species in
the current issue of the Journal of Vertebrate Paleontology,
after several seasons of collecting additional samples from the
field and analyzing them.

"This study is the culmination of a lot of work in the field, in
the fossil lab, and in the office," Downs said.

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